In recent years, technology has been proposed that enables the efficient production of monocyclic aromatic hydrocarbons having a carbon number of 6 to 8 (such as benzene, toluene and crude xylene, which are hereafter jointly referred to as “BTX”), which can be used as high-octane gasoline base stocks or petrochemical feedstocks and offer significant added value, from feedstock oils containing a polycyclic aromatic hydrocarbon fraction such as light cycle oil (hereafter also referred to as “LCO”), which is a cracked light oil produced in a fluid catalytic cracking (hereafter also referred to as “FCC”) apparatus.
One example of a known method for producing BTX from a polycyclic aromatic fraction is a method in which a feedstock oil is brought into contact with a catalyst, and a cracking and reforming reaction is induced to obtain a product containing monocyclic aromatic hydrocarbons having a carbon number of 6 to 8.
Known reaction systems for conducting the cracking and reforming reaction include various processes such as fixed bed, fluidized bed and moving bed systems, but a fixed bed system is advantageous for reasons including inexpensive construction costs and operating costs.
When a process such as the aforementioned cracking and reforming reaction is conducted to produce monocyclic aromatic hydrocarbons, a zeolite catalyst having acid sites (a crystalline aluminosilicate catalyst) is typically used as the catalyst. At the laboratory level, this type of zeolite catalyst is able to maintain its performance in a favorable state, and is therefore typically used as is, without adding a binder. However, in a fixed bed reaction tower, particularly at the level of an actual production plant, in order to compensate for a lack of strength, a binder is used to create a molded catalyst, despite this causing a slight deterioration in the catalyst performance.
In other words, in order to ensure that the catalyst does not create obstacles to operation, for example due to the catalyst powdering during operation and disturbing the flow of the oil through the reaction tower, or due to the powdered catalyst frequently blocking the filter provided at the outlet of the reaction tower, a molded zeolite catalyst prepared using a binder or the like is often used.
Examples of this type of zeolite catalyst that has been molded using a binder include the catalyst disclosed in Patent Document 1. The zeolite catalyst disclosed in Patent Document 1 is used for alkylating mainly aromatic compounds, such as the methylation of toluene, and is formed by treating a zeolite with a phosphorus compound to form a phosphorus-treated zeolite, heating the phosphorus-treated zeolite at a temperature of 300° C. to 400° C., mixing the heated phosphorus-treated zeolite with an alumina-containing binder to form a zeolite-binder mixture, and then heating the zeolite-binder mixture at a temperature of 400° C. or higher.